Packet-based feedback control of electrical drive and its application to trajectory tracking of manipulator

In systems disconnected from the external grid, such as mobile robots and vehicles, the effective use of renewables and energy harvesting techniques helps a longer operation with less weight and space for batteries. Power packet dispatching system is a promising measure to manage the complex power flow created by such distributed power sources of various profiles. In the system, power is transferred as a pulse, and information tag is attached to the pulse power in voltage waveforms. The physical integration of power and information realizes a smooth inclusion of sources and loads of different profiles and their decentralized operation. This paper discusses the application of the system to load control. We propose a decentralized packet‐based feedback control scheme. The successful operation of the proposed scheme is confirmed by an application to an electrical drive. In addition, the application to trajectory control of 2‐degree‐of‐freedom manipulator reveals the possibility of a peak‐power reduction based on a demand response operation of the proposed scheme. The results contribute to a realization of decentralized flow control of power packets based on the convenience of both the sources and the loads

Design and Lessons Learned on the Development of a Cryogenic Pupil Select Mechanism Used in the Testing and Calibration of the Integrated Science Instrument Module (ISIM) on the James Webb Space Telescope (JWST)

Calibration and testing of the instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) is being performed by the use of a cryogenic, full-field, optical simulator that was constructed for this purpose. The Pupil Select Mechanism (PSM) assembly is one of several mechanisms and optical elements that compose the Optical Telescope Element SIMulator, or OSIM. The PSM allows for several optical elements to be inserted into the optical plane of OSIM, introducing a variety of aberrations, distortions, obscurations, and other calibration states into the pupil plane. The following discussion focuses on the details of the design evolution, analysis, build, and test of this mechanism along with the challenges associated with creating a sub arc-minute positioning mechanism operating in an extreme cryogenic environment. In addition, difficult challenges in the control system design will be discussed including the incorporation of closed-loop feedback control into a system that was designed to operate in an open-loop fashion

Implementation and verification of a lunar mission subsystems

This final project is to implement and verify some of the subsystems that make up the Lunar mission designed by the team FREDNET Team (www.teamfrednet.org) for the Google Lunar X Prize, a competition to land on the moon in 20XX, collaborating on the design of some components. This project is developed in collaboration with other researchers of many nationalities and therefore needs to be part of the group in a real project focused on the use of open source software and the Internet community. Especially important is the development of, with our collaboration, one of the possible Rovers (vehicle that will move through the lunar surface) under the name of Pico-Rover. Highlights its particular design, emulating a small ball. We can develop a new concept of proposing Rovers miniaturization and cost reduction by applying concepts of physics but unconventional or usual (by now, all are Rovers used have low manoeuvrability and very high cost). Especially, we have studied and developed a short-range communication to allow the sending and receiving data to the Rover as images, video, telemetry, etc, and accelerometers to achieve radio-control and autonomous Rover control. Furthermore, we proceed to the study, construction and testing of communications boards CAN-Do for possible use in the Lunar Bus and / or Lunar Lander, which will commented in detail later. It has also initiated an investigation to give the Rover a system for detecting obstacles under the name of PicoSAR (micro-RADAR). It has also studied possible characteristics of a satellite link between the Rover and the Lunar Lander, which allows you to be in contact with the Rover. It is a very ambitious project, but which also allows us to participate in an innovative and very interesting format that we can already say that we are an important part in the team

MSAT-X: A technical introduction and status report

A technical introduction and status report for the Mobile Satellite Experiment (MSAT-X) program is presented. The concepts of a Mobile Satellite System (MSS) and its unique challenges are introduced. MSAT-X's role and objectives are delineated with focus on its achievements. An outline of MSS design philosophy is followed by a presentation and analysis of the MSAT-X results, which are cast in a broader context of an MSS. The current phase of MSAT-X has focused notably on the ground segment of MSS. The accomplishments in the four critical technology areas of vehicle antennas, modem and mobile terminal design, speech coding, and networking are presented. A concise evolutionary trace is incorporated in each area to elucidate the rationale leading to the current design choices. The findings in the area of propagation channel modeling are also summarized and their impact on system design discussed. To facilitate the assessment of the MSAT-X results, technology and subsystem recommendations are also included and integrated with a quantitative first-generation MSS design

Design of Control System with Feedback Loop for a Pulsatile Pump

This paper describes the design and implementation of a closed-loop proportional, integral, differential (PID) control system for a custom in-house pulsatile pump apparatus for the University of Arkansas Biomedical Department. The control system is designed to control a MOONS’ PL34HD0L8500 hybrid stepper motor using a dual H-bridge motor driver network with four pulse-width modulated (PWM) inputs to drive a pulsatile pump apparatus at motor stepping frequencies up to 2kHz. The speed of the motor is controlled from a pressure profile transmitted from an external source over RS-232 communication that specifies the motor speed, number of datapoints, and an array of pressure data. Data will be measured from the pump using pressure, flow, and temperature sensors that will output analog data and be read to the control board using analog-to-digital converters (ADCs). A PID controller will be used to match the speed of the motor to the control data by calculating the error between the sensor outputs and the desired profile. The circuit board is separated into two sections for the control board and motor circuit to isolate the 68V and motor circuity from the rest of the control board circuitry. The control system circuitry was tested, and while the control board systems were found to be functional, the motor circuit was found inefficient due to the high L/R time constant of the motor, resulting in greatly reduced speed and torque. A new chopper driver design was proposed to solve this issue and simulations conducted through MATLAB Simulink to prove the feasibility of the design

TITAN Wireless Camera Control System

The Titan Camera Control System is an eletromechanical device that allows the user to wirelessly control a camera’s digital operations as well as physical orientation through the use of a mobile device application. The Titan system accepts input in the form of virtual user commands on the mobile app and performs system output in the form of sending photos/video from the camera back to the app as well as changing the orientation of the camera in accordance with the user’s commands

Phase-referenced Interferometry and Narrow-angle Astrometry with SUSI

This thesis describes the development of an astrometric facility at the Sydney University Stellar Interferometer (SUSI) with an aim to measure at high precision the relative astrometry of bright close binary stars and ultimately to detect the presence of exoplanets within those binary star systems through observations of the systems’ perturbed motion. At the core of the facility is a new beam combiner that is phase-referenced to an existing primary beam combiner in the visible wave- length regime. The latter provides post-processed fringe-tracking information to the former for fringe stabilization and coherent integration of pre-recorded stellar fringes using newly developed data reduction software. Interference fringe packets of a binary star are recorded alternately; first the fringe packet of the primary, then the secondary, finally back to the primary again. The measurement of the fringe packet separation is facilitated by an air-filled differential delay line and a network of interferometer-based metrology systems. Characterizations and initial astronomical observations carried out with the dual beam combiner setup demonstrated for the first time the success of the dual-star phase-referencing technique in visible (~1μm) wavelengths. The current astrometric precision is larger than 100μas while the long term astrometric accuracy is yet to be characterized. In a parallel development, a complementary observing method using only the primary beam combiner is also demonstrated in this thesis. Relative astrometry of binary stars up to ~0.8” separation with this technique has been demonstrated to have precision of better than 100μas. A simple detection limit analysis based on a list of target binary stars estimates up to two exoplanet detections can be achieved with SUSI if the new astrometric facility attains precision of 10μas while the primary beam combiner operates at its designed peak performance. Finally, one new stellar companion was resolved and a preliminary astrometry for another suspected companion was estimated from the astronomical observation data collected throughout the course of this thesis

Phase-referenced Interferometry and Narrow-angle Astrometry with SUSI

This thesis describes the development of an astrometric facility at the Sydney University Stellar Interferometer (SUSI) with an aim to measure at high precision the relative astrometry of bright close binary stars and ultimately to detect the presence of exoplanets within those binary star systems through observations of the systems’ perturbed motion. At the core of the facility is a new beam combiner that is phase-referenced to an existing primary beam combiner in the visible wave- length regime. The latter provides post-processed fringe-tracking information to the former for fringe stabilization and coherent integration of pre-recorded stellar fringes using newly developed data reduction software. Interference fringe packets of a binary star are recorded alternately; first the fringe packet of the primary, then the secondary, finally back to the primary again. The measurement of the fringe packet separation is facilitated by an air-filled differential delay line and a network of interferometer-based metrology systems. Characterizations and initial astronomical observations carried out with the dual beam combiner setup demonstrated for the first time the success of the dual-star phase-referencing technique in visible (~1μm) wavelengths. The current astrometric precision is larger than 100μas while the long term astrometric accuracy is yet to be characterized. In a parallel development, a complementary observing method using only the primary beam combiner is also demonstrated in this thesis. Relative astrometry of binary stars up to ~0.8” separation with this technique has been demonstrated to have precision of better than 100μas. A simple detection limit analysis based on a list of target binary stars estimates up to two exoplanet detections can be achieved with SUSI if the new astrometric facility attains precision of 10μas while the primary beam combiner operates at its designed peak performance. Finally, one new stellar companion was resolved and a preliminary astrometry for another suspected companion was estimated from the astronomical observation data collected throughout the course of this thesis

HATSouth: a global network of fully automated identical wide-field telescopes

HATSouth is the world's first network of automated and homogeneous telescopes that is capable of year-round 24-hour monitoring of positions over an entire hemisphere of the sky. The primary scientific goal of the network is to discover and characterize a large number of transiting extrasolar planets, reaching out to long periods and down to small planetary radii. HATSouth achieves this by monitoring extended areas on the sky, deriving high precision light curves for a large number of stars, searching for the signature of planetary transits, and confirming planetary candidates with larger telescopes. HATSouth employs 6 telescope units spread over 3 locations with large longitude separation in the southern hemisphere (Las Campanas Observatory, Chile; HESS site, Namibia; Siding Spring Observatory, Australia). Each of the HATSouth units holds four 0.18m diameter f/2.8 focal ratio telescope tubes on a common mount producing an 8.2x8.2 arcdeg field, imaged using four 4Kx4K CCD cameras and Sloan r filters, to give a pixel scale of 3.7 arcsec/pixel. The HATSouth network is capable of continuously monitoring 128 square arc-degrees. We present the technical details of the network, summarize operations, and present weather statistics for the 3 sites. On average each of the 6 HATSouth units has conducted observations on ~500 nights over a 2-year time period, yielding a total of more than 1million science frames at 4 minute integration time, and observing ~10.65 hours per day on average. We describe the scheme of our data transfer and reduction from raw pixel images to trend-filtered light curves and transiting planet candidates. Photometric precision reaches ~6 mmag at 4-minute cadence for the brightest non-saturated stars at r~10.5. We present detailed transit recovery simulations to determine the expected yield of transiting planets from HATSouth. (abridged)Comment: 25 pages, 11 figures, 1 table, submitted to PAS